Therefore he would undertake a warlike expedition in the following spring, but in the meantime he would continue with Mackenzie as long as he wanted him.
Mackenzie, rejoining Le Roux at the Slave Lake, safely reached his station at Fort Chipewayan on September 12, 1789, just as the approach of winter was making travel in these northern regions dangerous to those who relied on unfrozen water as a means of transit.
Mackenzie seems to have been a little disappointed with the results of his northward journey; perhaps he had thought that the outlet of Slave Lake and the Mackenzie River would be into the Pacific, the _Mer de l'Ouest_ of his Canadian _voyageurs_.

Yet he must have realized that he had discovered something very wonderful after all: the beginning of Alaska, the approach to a region which, though lying within the Arctic circle, has climatic conditions permitting the existence of trees, abundant vegetation, and large, strange beasts, and which, moreover, is highly mineralized.

His work in this direction, however (and that of Hearne), was to be completed in the next century by SIR JOHN FRANKLIN, SIR GEORGE BACK, SIR JOHN RICHARDSON, and SIR JOHN ROSS--all knighthoods earned by magnificent services in geographical exploration--and by THOMAS SIMPSON, Dr.John Rae,[3] WARREN DEASE, JOHN M'LEOD, ROBERT CAMPBELL, and other servants of the Hudson's Bay Company.
[Footnote 3: See p.

125.] In October, 1792, Mackenzie had determined to make a great attempt to reach the Pacific Ocean.

By this time he and his colleagues had explored the Peace River (the main tributary of Slave Lake), and had realized that they could travel up it into the heart of the Rocky Mountains.